bash

Table of contents

  1. ls
  2. grep vs find
    1. grep
    2. find

ls

  • ls short for listing files in the current dir.
  • ls -a to list all files including hidden ones (those start with a dot).
  • ls -l to list files in long format (vertically), +permissions, owner, size
  • ls -h to list file sizes in human-readable format (e.g., KB, MB).
  • ls -t to sort files by modification time, newest first.
  • ls -r to reverse the order of the sort.

grep vs find

  • grep is used to search for specific patterns within the content of files, while find is used to search for files and directories based on their names, types, sizes, or other attributes.

grep

  • grep short for global regular expression print, used to search for specific patterns in files or output.
  • grep file content?
    • grep "pattern" filename to search for “pattern” in a file.
    • grep -r "pattern" directory/ to search recursively in a directory.
    • grep -r "pattern" filename to search recursively in a specific file.
    • grep -i "pattern" filename to search case-insensitively (i.e. ERROR, error, Error).
    • grep -n "pattern" filename to include line numbers in the output.
      • Example: the is is all in red, and the line numbers are in green (?)
              [12:02:07]miltonycchow@HP-Miller: ~$ grep -rin "is" .tmp.test.txt 
      1:This is a new line
      2:The is another new line
    • grep -v "pattern" filename to invert the match, showing lines that do NOT contain the pattern.
    • grep -l "are" ~ to list only the names of files that contain the pattern “are”. –> This won’t work since ~ is a dir, so we need recursive search, aka: grep -rl "are" ~

find

  • find is used to search for files and directories in a directory hierarchy based on various